To perform satisfactorily, an air filter spreads a filter media over a surface area through which air passes. As the surface area increases, it becomes easier for the air to pass through the filter without requiring a high-powered fan to promote air circulation. However, as the surface area of the filter media increases, the frame usually increases in size to support the filter media over the larger surface area.
A typical disposable furnace filter can run as large as twenty inches square, twenty by twenty-five inches or even larger. Even though they are only a few inches thick, a large amount of space is needed to package, ship, warehouse, store and display the filters as they move from the manufacturing facility to the consumers' hands. If the volume of this product could be reduced, the cost of packaging, storage, shipping the filters could be reduced since these steps are priced primarily by volume.
Other attempts have been made to reduce the size of furnace filters prior to use in a furnace. A media filter cabinet is described in U.S. Pat. No. 6,502,909. It is shipped in a collapsed form and assembled prior to use. Top, front, back and bottom pieces each have a plurality of slots and tabs that interfit, forming the cabinet. It is secured with a single screw following assembly. A retaining bracket and wire, which must be sized to fit a particular filter, form a smaller compartment for a smaller filter. The retaining bracket has a flange that attaches to a receptacle in the front piece, locking with a quarter turn. The cabinet is collapsible diagonally upon removal of the retaining bracket, back panel and the door that attaches to the front piece. Although the filter cabinet does collapse, the manner in which it does so makes it inconvenient to reassemble prior to use.
A collapsible shipping container is discussed in U.S. Pat. No. 5,190,179. This container has an open construction with no panels covering the frame top and bottom. The end walls pivot inwardly of the container on hinges, allowing the top and end walls to lie on the bottom wall when collapsed.
Although collapsible filter frames and filters are known, they can be inconvenient or difficult to use. A consumer purchasing a furnace filter is unlikely to spend time reassembling a filter or getting out tools needed to put it together. Further, to justify the time spent deploying the filter, it should cost less than a conventional furnace filter.